Failed to initialize language server - How to troubleshoot?

How do I troubleshoot this? It seems to happen on a couple specific projects. Eclipse -clean, restart, copilot SSL, copilot workspace context does not make any difference. Something with the preferences seems to affect the copilot initialization. It works when I restart with a clean workspace with no preferences, but I really don't want to do that because I have extensive customizations for eclipse preferences. And I can't figure out which preferences are causing this problem. I'm on the current Eclipse and copilot plugin version, authenticating to github.com for copilot license initialization. Windows 11, Java 17 and 21. This is the only detail I have from the error logs:

!ENTRY com.microsoft.copilot.eclipse 4 0 2025-08-19 14:50:02.067
!MESSAGE [Error] Failed to start copilot language server.
!STACK 0
java.lang.IllegalStateException: Failed to start copilot language server.
	at com.microsoft.copilot.eclipse.ui.CopilotUi$1.run(CopilotUi.java:73)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

!ENTRY org.eclipse.core.jobs 4 2 2025-08-19 14:50:02.074
!MESSAGE An internal error occurred during: "Copilot initialization".
!STACK 0
java.lang.IllegalStateException: Failed to start copilot language server.
	at com.microsoft.copilot.eclipse.ui.CopilotUi$1.run(CopilotUi.java:73)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

!ENTRY com.microsoft.copilot.eclipse 1 0 2025-08-19 14:50:02.221
!MESSAGE [Info] Starting language server with binary lsp agent.

Is there any more logs reported by copilot plugin for this session?

That is from the Eclipse error log. There is also a dedicated log for "Copilot MCP".
In Eclipse go to the "Console" and there Press on the small "Computer" icon "Display Selected Console"
In that menu select "Copilot (MCP)". There you may get more details about what goes wrong. Good luck

Same problem here, on Linux.
Seems like a matter of timing around the execution of that com.microsoft.copilot.eclipse.ui.CopilotUi$1.run(),
or, therein, a missing explicit await or dependency on the language server startup:
When I manually, in a debugger, put a breakpoint in org.eclipse.core.internal.jobs.Worker.run(), and delay the execution of that com.microsoft.copilot.eclipse.ui.CopilotUi$1.run() compared to other jobs, so the language server really was started up first, that "Copilot initialization" seems to succeed in this instance of the Eclipse IDE.

And: There doesn't seem to be a Console for "Copilot (MCP)" at all.
Do I need to configure something to enable that Console?

Michael Haubenwallner (@haubi)

Michael Haubenwallner (@haubi) There should be some error logs in the Error Log view, could you pls check and maybe share a screenshot?

The message box is:

The Error Log view shows:

And the workspace .metadata/.log file contains:

!SESSION 2025-09-15 08:42:17.878 -----------------------------------------------
eclipse.buildId=4.35.0.I20250228-0140
java.version=21.0.7
java.vendor=Eclipse Adoptium
BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en
Command-line arguments:  -os linux -ws gtk -arch x86_64

!ENTRY com.microsoft.copilot.eclipse 4 0 2025-09-15 08:42:29.258
!MESSAGE [Error] Failed to start copilot language server.
!STACK 0
java.lang.IllegalStateException: Failed to start copilot language server.
        at com.microsoft.copilot.eclipse.ui.CopilotUi$1.run(CopilotUi.java:78)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

!ENTRY org.eclipse.core.jobs 4 2 2025-09-15 08:42:29.265
!MESSAGE An internal error occurred during: "Copilot initialization".
!STACK 0
java.lang.IllegalStateException: Failed to start copilot language server.
        at com.microsoft.copilot.eclipse.ui.CopilotUi$1.run(CopilotUi.java:78)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

!ENTRY com.microsoft.copilot.eclipse 1 0 2025-09-15 08:42:29.273
!MESSAGE [Info] Starting language server with binary lsp agent.

!ENTRY com.microsoft.copilot.eclipse 1 0 2025-09-15 08:42:29.274
!MESSAGE [Info] Found native binary in fragment bundle: com.microsoft.copilot.eclipse.core.agent.linux.x64

!ENTRY com.microsoft.copilot.eclipse 1 0 2025-09-15 08:42:29.280
!MESSAGE [Info] Lsp agent started successfully.

!ENTRY org.eclipse.lsp4e 1 0 2025-09-15 08:42:30.941
!MESSAGE [Info] [lsp] GitHub Copilot Language Server 1.363.0 initialized

!ENTRY org.eclipse.ui 2 2 2025-09-15 08:44:05.048
!MESSAGE Invalid preference category path: org.eclipse.ease.preferences.global (bundle: org.eclipse.ease.lang.python.jython, page: org.eclipse.ease.lang.python.jython.libraryPrefPage)

!ENTRY org.eclipse.ui 2 2 2025-09-15 08:44:05.048
!MESSAGE Invalid preference category path: org.eclipse.wst.html.ui.preferences.web (bundle: org.eclipse.wst.jsdt.ui, page: org.eclipse.wst.jsdt.ui.preferences.JavaBasePreferencePage)

Meanwhile I've found https://github.com/orgs/community/discussions/151288#discussioncomment-14287359
which describes what I can reproduce on Linux:

During initial workspace setup, the Chat view is not initialized yet, and the Language Server is started later on.
Restarting Eclipse does not show the problem again, because Chat view is already registered for early loading, but
closing the Chat view brings back the problem after Eclipse restart.

Michael Haubenwallner (@haubi)

Hi Michael Haubenwallner (@haubi), thank you for reporting this.

I tried several times to reproduce the issue and do have success for one time.

I guess it's related with the race condition between the activation of core and ui plugin. (Though the ui will wait for the job from core completed, but it is not enough if the wait logic is called before core gets activates.)

I will work on a fix and release it to the nightly build channel once it's merged. Would it be possible for you help verify the fix once it's available? Thanks!

Andrey Loskutov (@iloveeclipse)

Andrey Loskutov (@iloveeclipse) Have you ever encountered this problem before?

I'm planing to add

// Explicitly activate the core bundle first
Bundle coreBundle = Platform.getBundle(CopilotCore.PLUGIN_ID);
if (coreBundle != null && coreBundle.getState() != Bundle.ACTIVE
        && coreBundle.getState() != Bundle.STARTING) {
    coreBundle.start(Bundle.START_TRANSIENT);
}

before

Job.getJobManager().join(CopilotCore.INIT_JOB_FAMILY, null);

In CopilotUi.start()

Does the change make sense from your point of view?

Does the change make sense from your point of view

Core bundle should be already automatically started if any of the classes from it are used by Copilot UI. So I would not add any manual "hacks" to start it.

Bob Fields (@bobfields)

Bob Fields (@bobfields) Michael Haubenwallner (@haubi) Is the problem stably reproducible on your side?

It is stably reproducible when our own plugin is installed, but IIRC I've also seen it once with some vanilla upstream setup, although not stably reproducible there.

Maybe irrelevant, but what I've also discovered is a difference on which thread executes com.microsoft.copilot.eclipse.ui.CopilotUi.start() method, i.e. which thread does activate the com.microsoft.copilot.eclipse.ui bundle:

from within thread main : seems to work (more likely),
from within thread Worker-#: Executing the early startup extensions: seems to break (more likely)

However, I've no idea about the conditions for which thread is the first one to activate (need) some bundle.

Andrey Loskutov (@iloveeclipse)

I paid attention to this issue recently. Though that it cannot be stably reproduced, but I did encounter it several times.

But I've no idea why it will happen.

Given that the MANIFEST.MF declares that UI requires core, will OSGi guarantee that the CopilotCore.start() will be executed before CopilotUi.start()? Andrey Loskutov (@iloveeclipse) do you have any insight?

Given that the MANIFEST.MF declares that UI requires core, will OSGi guarantee that the CopilotCore.start() will be executed before CopilotUi.start()

The point is not about dependency (which is correct), but about class loading.
CopilotCore.start() will be executed before CopilotUi.start() if some of the classes from CopilotCore bundle would be used by any other bundle (e.g. UI plugin code executed on start() would refer to some core plugin API). (Another possibility would be to specify start level of core bundle, but this is not what you want to do in your code.)

UI plugin code executed on start() would refer to some core plugin API

UI do refer some code from core

Is this what you mean?

Is this what you mean?

No. Imports are not doing anything, they are needed only at compile time for compiler. I mean UI calling some code from core bundle.

I think it does:

https://github.com/eclipse-copilot/eclipse-copilot/blob/9fc215b436968b7b7274048e7e8c2dc837a75ccd/org.eclipse.copilot.ui/src/org/eclipse/copilot/ui/CopilotUi.java#L84

But it's wrapped in a job

But it's wrapped in a job

Just move CopilotCore.getPlugin() outside of the job and you are done.

Kimin Ryu (@workspace)

When it actually does initialize, now I get this error, not sure how to manually install the missing dependency:
Failed to install terminal bundle
Could not resolve module: com.microsoft.copilot.eclipse.ui.terminal [1095]
Unresolved requirement: Require-Bundle: org.eclipse.terminal.view.ui
The initialization error varies by the projects loaded in the Workspace. Exporting preferences, creating a new workspace, and importing preferences still shows the issue. Clean does not help. Closing all projects and restarting (with or without clean) does not seem to help. Removing Kimin Ryu (@workspace) from context does not help. There is no additional info in the error log. The only thing that works is starting over with a fresh workspace, where I lose all my preferences and test/run configurations.
This is very frustrating because VSCode does not work well with Java/Maven projects where the repo and settings are customized.
Is there some other plugin I can disable or other workspace setting I can change?
Please help fix this issue.

Unresolved requirement: Require-Bundle: org.eclipse.terminal.view.ui

It is this issue: #26
You need terminal bundles from latest 4.37 Eclipse update site.

In real simple terms...
Add update site 'https://download.eclipse.org/releases/latest'
Select the TM Terminal features to install. - This fixes the terminal bundle error.

Another user suggested having the Copilot chat view open/selected before restarting. Somehow that means it gets initialized first in the Eclipse UI when starting. I was going crazy trying to figure out why initialization would fail with no workspace projects, just after importing workspace preferences. That seems to 'fix' the issue, I just have to make sure Copilot chat is selected before shutting down the workspace.

Sheng Chen (@jdneo)

But it's wrapped in a job

Just move CopilotCore.getPlugin() outside of the job and you are done.

Sheng Chen (@jdneo) Kindly asking if there is some newer version than 0.11.0 around meanwhile, supposed to have this issue fixed?

Michael Haubenwallner (@haubi)

Hi Michael Haubenwallner (@haubi)

We just published a nightly build, could you please check if the issue is fixed?

https://marketplace.eclipse.org/content/github-copilot-nightly

The issue I reported below has been completely resolved in this nightly build.
Thank you so much!
https://github.com/orgs/community/discussions/151288#discussioncomment-14287359

Hi @haubi

We just published a nightly build, could you please check if the issue is fixed?

https://marketplace.eclipse.org/content/github-copilot-nightly

Yes, initialization seems to work more robust now, thanks!

(have not tested any functionality yet, need to clarify legal & licensing here still)

Michael Haubenwallner (@haubi)

need to clarify legal & licensing here still

Michael Haubenwallner (@haubi) what legal concern do you have? Anything we can help?

need to clarify legal & licensing here still

@haubi what legal concern do you have? Anything we can help?

As far as I understand, the concern is about whether to give Copilot access to our proprietary code, as well as the licensing costs.
So far, solving these concerns is nothing I'm involved with, and they are being worked out by other channels.
But thanks for the offer!

Sunbelt Computer Software

PL/B Language Development and Support

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Failed to initialize language server - How to troubleshoot? #21

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Failed to initialize language server - How to troubleshoot? #21

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